Winches are known to persons skilled in the art to have a wide range of applications wherever there is a requirement for lifting and releasing of load, involving a high torque. For example in oil platforms, floating platforms, sailing boats, elevators, anchoring of boats, drilling operations, cargo loading and unloading, E.O.T cranes, building constructions and so on.
It is also known that diesel electric propulsion drives are used to propel a floating vessel and require high power to be transmitted from the motor to the propeller.
Further, tidal power plants are known to be designed to transform the movement of the water to electric power. This requires high power to be transmitted.
The present invention will be explained primarily with reference to as a drive for a winch but it is equally effective in its application as diesel engine propulsion drives for floating vessels and as drives for generation of electricity, in tidal power plants and the like.
Different types of winches, having multifarious applications are already known as stated hereinbefore. WO2008/104060 discloses a winch which facilitates erecting and collapsing a vertical axis turbine. WO2010/004314 discloses application of winch for connecting a first body to a second body in an off shore environment. WO2009/028927 discloses a traction winch for a cable or the like intended to haul very heavy loads by means of cables for offshore abandonment recovery, oceanography and dredging at great depths. WO2008/153295 discloses application of a winch as a lifting device of a fire escape apparatus.
In all the aforesaid prior art documents, focus has been on the winch rather than on the unit for driving the winch. Driving units for winches are also known. An axial drive means has been disclosed in WO2010/004314 for maintaining correct spooling of the winch line. However, here the focus is on the construction of the winch rather than on its drive unit. Similarly, WO2009/062232 discloses a drum winch which has application in marine vessels as an anchor drum winch. Here, the focus is on the aspect that the winch drum can rotate independently of the drive shaft. Although, this prior art discloses a drive unit coupled to the drive shaft, it does not focus on the constructional features of the drive unit of the winch. Rather, it states that the drive unit may adopt any suitable form and that the exact nature of the drive unit is not consequential to the invention.
The hunt for constructing efficient drive units for winches has witnessed several prior patents/patent publications. U.S. Pat. No. 4,565,352 discloses a winch drive with an internally arranged planet gear and a motor for driving the winch drum. The motor is secured to the frame at one front end of the drum and the drive shaft of the motor is drivingly connected to the driven input of the planet gear. WO2006/117607 discloses a driving means for a winch, for conveying rotational movement from hub to the drive assembly. The winch has a hub, a guiding system for distributing cable about the hub and a drive assembly connected to the guiding system. This assembly distributes the cables in two directions, for which it has a switch. The driving means comprises a first sprocket and a second sprocket connected to the drive assembly and a chain which connects the first sprocket and second sprocket. WO2009/142573 essentially discloses a drive unit having a rotatably mounted rope drum and a shaft driving the same via transmission means and a crank, the latter having a driving shaft using at least two different gearing means.
The drive units disclosed in the above documents do not focus on achieving compactness, on reducing the number of components and on light, weight and on ensuring that the torque over the drive shaft is balanced. This is not only true for winch drives, but also for drives for propelling floating vessels where the requirement for transmitting high power from the motor to the propeller exists. This is also true for drives for generating electricity in tidal power plants, where the drive performs the role of gearing up the electric generator. In such drives also, requirement for transmission of high power exists.
A drive unit for a wind mill is described in an at the present time unpublished patent application PCT/EP2010/050987 by the same applicant and inventor. This prior application relates to the use as a wind mill drive only, but some of the basic ideas of the prior application is used in the present invention for other purposes than a wind mill drive.
Hence, there was a long felt need to construct a drive device for a winch/floating vessel propeller/tidal plant which is compact, ensures that the torque over the drive shaft is balanced, is light weight and also has substantially reduced number of components. The drive device according to the present invention meets this long felt need and other needs associated therewith and the construction of the drive device as disclosed hereinafter, is consequential to the present invention.